Most conventional CNG stations are custom designed for specific site conditions, and must operate within predetermined inlet gas pressure and flow ranges. These stations usually take a long time to build, and since they are designed to meet specific site conditions, the flow capacity is limited by the inlet gas pressure available by the local gas utility. According to other known CNG designs, the site conditions are modified to meet the equipment design specifications by utilizing an inlet gas regulator. Due to compressor design limitations, these stations often have to sacrifice gas pressure by going through the inlet regulator. After the gas is de-pressurized by the inlet regulator, it is then re-pressurized in the compressor. This design is very energy inefficient since the gas pressure is lowered before recompression in the compressor. Both custom-designed and site-modified systems are generally fixed speed and do not permit flow capacity control.